Hollandse Kust (zuid) Alpha ready for action

4C Offshore | Tom Russell
By: 31/03/2022 TenneT

Hollandse Kust (zuid) Alpha, TenneT’s high voltage offshore grid connection for the
Hollandse Kust (Zuid) 1&2 offshore wind farms, is ready for use. Wind farm developer Vattenfall can now connect the wind turbines to the high voltage grid. On top of that, the Hollandse Kust (zuid) Beta topside was installed this week.

TenneT received the Grid Readiness certification from DNV GL for Hollandse Kust (zuid) Alpha on Tuesday March 22nd. This means that the offshore grid connection fully complies with the conditions set out in the so-called Offshore Wind Energy Development Framework.

Marco Kuijpers, Director of Large Projects Offshore, said: "With the energization of the Hollandse Kust (zuid) Alpha connection, the offshore grid that TenneT is building in the North Sea is starting to take shape. Hollandse Kust (zuid) Alpha is the first connection of an offshore wind farm to the Maasvlakte and has a capacity of 700 MW. The energization of Hollandse Kust (zuid) Beta later this year will add another 700 MW from wind farms Hollandse Kust (zuid) III and IV.”

Over the past years, contractor Petrofac has been working on the fabrication of two High Voltage Alternating Current (HVAC) transformer stations – also called topsides – Alpha and Beta at the Drydocks World fabrication yard in Dubai. The Alpha topside was installed on the jacket in the North Sea, about 20 kilometers off the coast of The Hague, on Sunday December 26th 2021. Sister topside Beta left the fabrication yard in Dubai last February and sailed on a Boskalis transport vessel in little over one month to the Alexiahaven on the Maasvlakte, where it arrived last week.

In the Alexiahaven, the Beta topside was loaded from the transport vessel onto the platform installation vessel Pioneering Spirit of offshore company Allseas, which then sailed to the installation location at sea. After completion of preparatory work, Pioneering Spirit accurately positioned the Beta topside on the jacket this week.

Sami Iskander, Petrofac Group Chief Executive: “The safe installation of the Beta topside is a significant milestone in the delivery of this important energy transition project. Everyone involved should be proud of this achievement.”
Marco Kuijpers adds: “I am very pleased that the project was installed safely and I compliment Petrofac and Allseas with this. Wind energy plays a crucial role in the energy transition, also in industry, and I am proud that TenneT, together with our partners, can contribute to a sustainable future in this way."


The Hollandse Kust (zuid) Alpha and Beta transformer platforms are part of the offshore grid connection project for the Hollandse Kust (zuid) offshore wind farms. The wind farms,  
Hollandse Kust (Zuid) 1&2 and Hollandse Kust (Zuid) 3&4, are being developed by Vattenfall, which secured the rights to the projects with subsidy free bids in March 2018 and July 2019. The sites are owned by Vattenfall (50.5% stake), BASF (24.3% stake), and Allianz (25.2% stake).

The wind farms are located between 18 and 36 kilometres off the Dutch coast, between the Hague and Zandvoort. They will be fitted with 140 units of Siemens Gamesa 11 MW, SG 11.0-200 DD offshore turbines. Once the wind farm is operational, the 140 wind turbines will produce more than 6 TWh of green electricity annually. Once fully operational, the wind farm will be the largest offshore wind farm in the Dutch waters with 140 wind turbines and a total installed capacity of 1.5 GW. The project is expected to become fully operational in 2023.

By the end of 2023, TenneT will have constructed 3,500 MW offshore grid connections for offshore wind farms in the Dutch North Sea. The first 1,400 MW has been realised with the delivery of Borssele Alpha and Beta in 2019 and 2020. It will now be the turn of Hollandse Kust (zuid) Alpha and Beta this year, followed by Hollandse Kust (noord) in 2023. TenneT is using five identical 700 MW transformer platforms for these wind farms. These platforms are located close to the wind farms and all five use the same type of 220 kV cable connection to the coast. Such standardisation enables TenneT to complete these projects more efficiently, more quickly and more economically.